An orally bioavailable, direct-acting inhibitor of HCV NS3/4A serine protease; inhibits HCV replication in stable Huh7-derived replicon cell lines infected with subgenomic genotypes 1a, 1b, 2a, 3a, 4a, and 6a (EC50s = 1, 0.21, 5.3, 19, 0.09, and 0.69 nM, respectively); inhibits replicons from clinical isolates of genotypes 1a (EC50s = 0.43 to 1.87 nM) and 1b (EC50s = 0.033 to 0.087 nM)